U.S. patent number 4,306,908 [Application Number 06/188,746] was granted by the patent office on 1981-12-22 for ferromagnetic amorphous alloy.
This patent grant is currently assigned to Hitachi, Ltd., Hitachi Metals, Ltd., Hitachi Research Dev. Corp.. Invention is credited to Mitsuhiro Kudo, Yasunobu Ogata, Shigekazu Otomo, Yoshizo Sawada, Kazuo Shiiki, Shinji Takayama, Yasuo Tsukuda.
United States Patent |
4,306,908 |
Takayama , et al. |
December 22, 1981 |
**Please see images for:
( Certificate of Correction ) ** |
Ferromagnetic amorphous alloy
Abstract
A ferromagnetic amorphous alloy having a composition represented
by (Co.sub.x Ni.sub.y Fe.sub.z).sub.a M.sub.b G.sub.c, wherein M is
Cr, Mo and/or W, G is Zr, Hf and/or Ti and x, y, z and a, b, c are
selected to meet the conditions of x=1-y-z, 0.ltoreq.y.ltoreq.0.2,
0.ltoreq.z.ltoreq.0.7, a=1-b-c, 0.ltoreq.b.ltoreq.0.05 and
0.05.ltoreq.c.ltoreq.0.2 This amorphous alloy has a superior
magnetic characteristic and a high thermal stability.
Inventors: |
Takayama; Shinji (Tokyo,
JP), Tsukuda; Yasuo (Ome, JP), Shiiki;
Kazuo (Kanagawa, JP), Otomo; Shigekazu (Hachioji,
JP), Kudo; Mitsuhiro (Tokyo, JP), Ogata;
Yasunobu (Kumagaya, JP), Sawada; Yoshizo
(Saitama, JP) |
Assignee: |
Hitachi, Ltd. (Tokyo,
JP)
Hitachi Metals, Ltd. (Tokyo, JP)
Hitachi Research Dev. Corp. (Tokyo, JP)
|
Family
ID: |
14816618 |
Appl.
No.: |
06/188,746 |
Filed: |
September 19, 1980 |
Foreign Application Priority Data
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Sep 21, 1979 [JP] |
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54-121655 |
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Current U.S.
Class: |
148/403; 148/304;
420/435; 420/436; 420/442 |
Current CPC
Class: |
H01F
1/15316 (20130101); C22C 45/008 (20130101) |
Current International
Class: |
C22C
45/00 (20060101); H01F 1/153 (20060101); H01F
1/12 (20060101); C22C 019/00 () |
Field of
Search: |
;75/123H,123J,123K,123M,123,126D,126E,126F,126H,128R,128B,128Z,128T |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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49-74246 |
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Jul 1974 |
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JP |
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54-29817 |
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Mar 1979 |
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JP |
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Other References
Ray et al., "Electron Diffraction Study of a Noncrystalline Zr-Ni
Phase", Metallurgical Transactions vol. 4, Aug. 1973, pp.
1785-1790. .
Ray et al., "New Non-Crystalline Phases in Split Cool Transition
Metal Alloys" Scripts Metallurgica vol. 2, pp. 357-359, Apr. 29,
1968, Pergamon Press..
|
Primary Examiner: Rutledge; L. Dewayne
Assistant Examiner: Sheehan; John P.
Attorney, Agent or Firm: Craig and Antonelli
Claims
What is claimed is:
1. A ferromagnetic amorphous alloy having a composition expressed
by (Co.sub.x Ni.sub.y Fe.sub.z).sub.a M.sub.b G.sub.c, wherein M is
at least one transition metal element selected from the group
consisting of Cr, Mo and W, G is at least one element selected from
the group consisting of Zr, Hf and Ti and wherein x, y, z and a, b,
c are selected to meet the conditions of: x=1-y-z,
0.ltoreq.y.ltoreq.0.2, 0.ltoreq.z.ltoreq.0.7, a=1-b-c,
0.ltoreq.b.ltoreq.0.05 and 0.05.ltoreq.c.ltoreq.0.2.
2. A ferromagnetic amorphous alloy as claimed in claim 1, wherein
y, z and b meet the condition of y+z+b>0.
3. A ferromagnetic amorphous alloy as claimed in claim 1, wherein y
meets the condition of 0<y.ltoreq.0.2.
4. A ferromagnetic amorphous alloy as claimed in claim 1, wherein z
meets the condition of 0<z.ltoreq.0.7.
5. A ferromagnetic amorphous alloy as claimed in claim 1, wherein b
meets the condition of 0<b.ltoreq.0.05.
6. A ferromagnetic amorphous alloy as claimed in claim 1, wherein
y, z and b meet the conditions of 0<y.ltoreq.0.2,
0<z.ltoreq.0.7 and 0<b<0.05.
7. A ferromagnetic amorphous alloy as claimed in claim 1, wherein
z, b and c meet the conditions of z.apprxeq.0, b.apprxeq.0 and
c.apprxeq.0.1.
8. A ferromagnetic amorphous alloy as claimed in claim 7, wherein y
meets the condition of y.apprxeq.0.1.
9. A ferromagnetic amorphous alloy as claimed in claim 1, 2, 3, 4,
5, 6, 7 or 8, wherein the element represented by M is Cr.
10. A ferromagnetic amorphous alloy as claimed in claim 1, 2, 3, 4,
5, 6, 7 or 8, wherein the element represented by G is Zr.
11. A ferromagnetic amorphous alloy as claimed in claim 1, 2, 3, 4,
5, 6, 7 or 8, wherein elements represented by M and G are Cr and
Zr, respectively.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a ferromagnetic amorphous alloy
for use as material for magnetic appliances such as magnetic head,
transformer, magnetic shield and so forth and, more particularly,
to a ferromagnetic alloy of metal-metal amorphous alloy system
having a superior thermal stability, high saturation flux density
and substantially zero magnetic striction, usable in place of
conventional ferromagnetic alloy of metal-metalloid amorphous alloy
system.
It is known that, in some kinds of metal or alloy, it is possible
to obtain an amorphous structure in which orderly arrangement of
atoms is lost so far as a long range of atom arrangement is
concerned, by cooling the metal or alloy in a molten state at a
high cooling rate of about 10.sup.6 .degree.C./s under a specific
condition. In recent years, it has been made clear that, among the
amorphous alloys produced in the above-explained method, some
alloys exhibit superior characteristics which could never be
attained by the conventional crystalline alloys, such as high
strength, high ductility, and superior soft magnetic
characteristics, i.e. high saturation flux density and high
magnetic permeability. These alloys are of metal-metalloid
amorphous alloy system. A typical example of such alloys is an
alloy of Fe-Co-Si-B system. For instance, an alloy having a
composition of Fe.sub.4.5 Co.sub.70.5 Si.sub.15 B.sub.10 and an
alloy having a composition of Fe.sub.4.8 Co.sub.75.2 B.sub.20
exhibit saturation flux densities which are as high as 8 to 11 kG.
Since in the composition in which the ratio of Co to Fe contents is
maintained 94:6, the magnetic striction becomes substantially zero,
alloys having such composition can be used as the material of
magnetic head, with the advantage that the change of magnetic
permeability in the head production process is small. These
amorphous alloys, however, are thermally unstable and time
dependence is apt to occur regarding the magnetic characteristics
thereof, because they are in pseudo-equilibrium state. Such thermal
unstability is caused particularly in the amorphous alloys having
non-metallic content such as B, C, P and Si. Such thermal unstable
characteristic is considered to be caused by the diffusion and
segregation of the non-metallic elements. In addition, since the
non-metallic elements have no magnetic moment, the amorphous alloy
containing non-metallic elements exhibits saturation flux density
lower than that of the amorphous alloy consisting of only magnetic
metallic elements.
Thus, there has been a demand for improvement in the thermal
stability and saturation flux density of the metal-metalloid
amorphous alloy.
Japanese Patent Laid-open No. 29817/1979 can be picked up as a
reference showing a prior art relevant to the invention of this
application.
SUMMARY OF THE INVENTION
Under these circumstance, the present invention aims at providing
an amorphous alloy containing a ferromagnetic metal such as Co, Ni,
Fe as the major constituent and at least one metal element selected
from the group of Ti, Zr, and Hf as a glass former element, in
place of conventional non-metallic glass former elements such as B,
C, P or Si.
More specifically, the invention provides a ferromagnetic amorphous
alloy having a superior soft magnetic characteristic, which alloy
is made of an alloy system constituted by a major constituent of Co
and a glass former element of Zr and containing, as occasion
demands, Ni for reducing the magnetic striction substantially to
zero and/or Fe for improving the saturation flux density and/or at
least one element of VI group such as Cr, Mo, W for increasing the
hardness and crystallization temperature to thereby further improve
the thermal stability. A part or whole of Zr may be substituted by
Hf or Ti.
The ferromagnetic amorphous alloy of the invention can be expressed
by a formula of (Co.sub.x Ni.sub.y Fe.sub.z).sub.a M.sub.b G.sub.c,
wherein M is at least one transition element selected from a group
consisting of Cr, Mo and W, G being at least one element selected
from a group consisting of Zr, Hf and Ti. In the formula, x, y, z
and a, b, c are selected to meet the following conditions:
The saturation flux density may be lowered below 10 KG, when the
value of y exceeds 0.2 or when the value of b exceeds 0.05. Also,
the saturation flux density is rapidly lowered as the value of Z
exceeds 0.7. The amorphous structure can hardly be obtained when
the value of c representing the amount of Zr, Hf and/or Ti is less
than 0.05. A value of c in excess of 0.2 causes a drastic reduction
of saturation flux density and makes it extremely difficult to
obtain the amorphous structure.
The alloy of the invention is preferentially amorphous and the
diffraction pattern obtained through known X-ray diffraction
technique does not show sharp peak peculiar to crystals.
Any one of known production methods for producing an amorphous
alloy, such as single roller quenching method, twin roller
quenching method, rotating drum quenching method and spattering
method can be used for the production of the amorphous alloy of the
invention. The production can be made in any desired atmosphere
such as inert gas atmosphere, vacuum or atmospheric air.
The ferromagnetic amorphous alloy of the invention thus constituted
exhibits superior characteristics such as crystallization
temperature in excess of 450.degree. C. and saturation flux density
in excess of 10 KG. It is also possible to obtain an alloy having a
magnetic striction falling between +5.times.10.sup.-6 and
-5.times.10.sup.-6 (for instance, in a case of such constituents as
G is Zr, z and b nearly equal zero and c nearly equals 0.1) and
even another alloy having a magnetic striction of substantially
zero (for instance, in a case of such constituents as G is Zr, z
and b nearly equal zero and y and c nearly equal 0.1).
The values of y, z and b may be zero. Namely, the addition of Ni,
Fe, Cr, Mo and W is optional. It is, however, preferred to select
these values as follows when the above-mentioned effect is
necessary, that is, the addition of these elements provides the
aforementioned advantages:
In this case, the consumption of precious Co is reduced so that
reduction of production cost is achieved as an additional
advantage.
The use of Cr and Zr as M and G, respectively, is considered to be
appropriate because they can be obtained comparatively easily at a
relatively low cost.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram showing a Y-dependency of magnetic striction in
an amorphous alloy expressed by (Co.sub.1.0-y Ni.sub.y).sub.0.9
Zr.sub.0.1 ;
FIG. 2 is a diagram showing z-dependency of saturation flux density
in an alloy expressed by (Co.sub.1-z Fe.sub.z).sub.0.9 Zr.sub.0.1
;
FIG. 3 is a digram showing z-dependency and b-dependency of
crystallization temperature of alloys expressed by (Co.sub.1-z
Fe.sub.z).sub.0.9 Zr.sub.0.1 and Co.sub.0.9-b Cr.sub.b Zr.sub.0.1
;
FIG. 4 is a diagram showing how much the hardness is affected in
Co.sub.0.9-w Y.sub.w Zr.sub.0.1 system by an additional element Y
which is Fe, Cr or Ni; and
FIG. 5 is a graph showing the relationship between the annealing
temperature and fracture strain as observed in an amorphous alloy
embodying the present invention and a conventional amorphous
alloy.
DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[Example 1]
Among various methods of producing amorphous alloy heretofore
known, a single roller quenching method is a representative
production method suitable for mass-production. A matrix alloy
having a composition expressed by a general formula of (Co.sub.x
Ni.sub.y Fe.sub.z).sub.a M.sub.b Zr.sub.c, wherein M is at least
one element selected from the VI group elements consisting of Cr,
Mo and W (x=1-y-z, 0.ltoreq.y.ltoreq.0.2, 0.ltoreq.z.ltoreq.0.7,
a=1-b-c, 0.ltoreq.b.ltoreq.0.05 and 0.05.ltoreq.c.ltoreq.0.2) was
prepared and was then subjected to a single roller quenching
process conducted in an atmosphere of argon. As a result,
ferromagnetic amorphous alloys having superior thermal stability
and a high saturation flux density were obtained. In some of these
alloys the magnetic striction thereof becomes zero.
The production of these amorphous alloys is possible under any
atmosphere other than argon gas atmosphere, e.g. vacuum or
atmospheric air, and through any one of various methods such as
twin roller quenching process, rotating drum quenching process,
spattering process and so on.
In this example, a nozzle of 0.8 mm dia. was used for ejecting a
melt. The samples were produced using a copper roll of 400 mm dia.
rotated at a speed of 1500 r.p.m. and at a melt ejecting pressure
of 0.05 to 0.3 Kg/cm.sup.2.
FIG. 1 shows the value of magnetic striction of amorphous alloys of
composition expressed by (Co.sub.1-y Ni.sub.y).sub.0.9 Zr.sub.0.1
with the value of y being varied between 0 and 0.4, under
application of a magnetic field of 120 Oe, as a function of y. As
will be seen from FIG. 1, the magnetic striction takes a value of
between +5.times.10.sup.-6 and -5.times.10.sup.-6 when the value of
y is between 0 and 0.2. The saturation flux density of amorphous
alloy having a composition of Co.sub.0.8 Ni.sub.0.1 Zr.sub.0.1 is
11.3 KG which is equivalent to or higher than that of conventional
amorphous alloys of Fe-Co-B system and Fe-Co-Si system heretofore
reported.
The saturation flux density is linearly increased as Ni is
decreased. An alloy expressed by Co.sub.0.9 Zr.sub.0.1 showed a
saturation flux density which is as high as 12.4 KG. Thus, the
amorphous alloy of (Co.sub.1-y Ni.sub.y).sub.0.9 Zr.sub.0.1
exhibits a saturation flux density of 10 KG or more and a magnetic
striction falling between +5.times.10.sup.-6 and -5.times.10.sup.-6
when the value y falls between 0 and 0.2. The crystallization
temperature of this alloy was observed to be between about
450.degree. C. and about 500.degree. C. Substantially zero magnetic
striction was obtained with an alloy having a composition of
(Co.sub.0.9 Ni.sub.0.1).sub.0.9 Zr.sub.0.1 i.e. x.apprxeq.0.9,
y.apprxeq.0.1, z=0, a.apprxeq.0.9, b=o and c.apprxeq.0.1.
[EXAMPLE 2]
FIG. 2 shows how much the saturation flux density is varied by
addition of Fe to the alloy of Co.sub.0.9 Zr.sub.0.1. The
conditions of production of samples are identical to those of
Example 1. It will be seen that, in (Co.sub.1-z Fe.sub.z).sub.0.9
Zr.sub.0.1 alloy system, the saturation flux density is increased
in accordance with the increase of Fe and that a high saturation
flux density in excess of 12 KG is obtainable in the region of
Z.ltoreq.0.7.
It will be also seen from FIG. 2 that the saturation flux density
is rapidly lowered as the value z is increased beyond 0.7.
The relationship between the crystallization temperature and the
amount z or Fe is shown at FIG. 3, as well as the relationship
between the crystallization temperature and the amount b of Cr. As
will be clearly understood from FIG. 3, in the alloy of the
invention, the crystallization temperature is raised in accordance
with the increase of the amount z of Fe, and the thermal stability
is enhanced correspondingly.
[EXAMPLE 3]
In this case, an amorphous alloy expressed by (Co.sub.1-y
Ni.sub.y).sub.0.9-b Cr.sub.b Zr.sub.0.1 where 0.ltoreq.y.ltoreq.0.2
and 0.ltoreq.b.ltoreq.0.05 was produced in the same manner as
Example 1, and coercive force, saturation flux density,
crystallization temperature and bending characteristic after
annealing were measured.
The coercive force is monotonously decreased by addition of Cr
element to the (Co.sub.1-y Ni.sub.y).sub.0.9 Zr.sub.0.1 alloy. For
instance, the Co.sub.0.86 Cr.sub.0.04 Zr.sub.0.1 alloy exhibits a
coercive force which is as small as about 0.1 Oe or less, even in
the sample as it is produced. The same result is obtained in the
case in which Ni is added. However, since the saturation flux
density is decreased as the amount of addition of Cr increases, the
amount b of addition of Cr must be maintained 0.05 or less if
saturation flux density of 10 KG or higher is to be obtained.
The alloy of the invention exhibits a crystallization temperature
of 450.degree. C. or higher and, hence, there is obtained a high
thermal stability. Particularly, the addition of Fe, Cr, Mo and/or
W raises the crystallization temperature.
FIG. 3 shows, by way of example, how much the crystallization
temperature Tx is changed in accordance with the change of z and b
in the aforementioned (Co.sub.1-z Fe.sub.z).sub.0.9 Zr.sub.0.1
system and Co.sub.0.9-b Cr.sub.b Zr.sub.0.1 system alloys. It will
be understood that the crystallization temperature is raised in
accordance with the increase of z and b. The curves shown in FIG. 3
are plotted even in a range where b is greater than 0.05.
In order to investigate the embrittlement caused by annealing, an
annealing was conducted at 440.degree. C. in 30 minutes with
respect to Co.sub.0.9-w Cr.sub.w Zr.sub.0.1
(0.02.ltoreq.W.ltoreq.0.05) alloy having a thickness of about 20
.mu.m, with the result that there is obtained. Superior thermal
stability in such a degree as the 180.degree. bending thereof is
possible even after the annealing. Such a high thermal stability
could never be attained by conventional metal-metalloid amorphous
alloys. Thus, it was confirmed that the amorphous alloy of the
invention exhibits a high thermal stability.
Although the foregoing description is made on an assumption that Cr
is used, substantially equivalent advantage were confirmed with the
use of Mo or W in place of Cr. Substantially same result was also
obtained when two or more of elements Cr, Mo and W are used.
[EXAMPLE 4]
FIG. 4 shows how much the hardness of Co.sub.0.9-w Y.sub.w
Zr.sub.0.1 alloy (Y=Fe, Ni, Cr) is changed in accordance with the
variation in the amounts of elements added. The sample was produced
in the same manner as Example 1. In FIG. 4, it is shown that a
considerable improvement of hardness is achieved by addition of Fe,
Ni and Cr. Equivalent improvement in hardness was obtained when Mo
or W, which belongs to VI group in the periodic table as is the
case of Cr, is used in place of Cr.
[EXAMPLE 5]
In the alloy of the invention, the concentration of Zr is selected
to fall between 0.05 and 0.2. This is because the Zr concentration
less than 0.05 makes the amorphous structure hardly obtainable and
because the Zr concentration in excess of 0.2 causes a serious
reduction of saturation flux density, as well as difficulty in
formation of amorphous structure.
In the composition of the alloy of invention, a part or whole of Zr
can be substituted by Ti or Hf. For example, it was observed that
the alloys having compositions of Co.sub.0.913 Hf.sub.0.087 and
Co.sub.0.909 Zr.sub.0.048 Hf.sub.0.043 compositions had amorphous
structure. These amorphous alloys also showed high crystallization
temperatures exceeding 500.degree. C. Equivalent effect was
obtained with alloys of structures in which Hf is substituted by
Ti, e.g. Co.sub.0.907 Ti.sub.0.093 and Co.sub.0.911 Zr.sub.0.043
Ti.sub.0.046 as well as in the case of alloys in which both of Hr
and Ti are added, e.g. Co.sub.0.909 Hf.sub.0.047 Ti.sub.0.044.
[EXAMPLE 6]
Alloys having compositions of (Co.sub.0.72 Ni.sub.0.156
Fe.sub.0.024 Zr.sub.0.1).sub.95 Mo.sub.5, (Co.sub.0.72 Ni.sub.0.156
Fe.sub.0.024 Zr.sub.0.1).sub.95 W.sub.5, (Co.sub.0.72 Ni.sub.0.156
Fe.sub.0.024 Zr.sub.0.1).sub.95 Cr.sub.5, Co.sub.72 Ni.sub.15.6
Fe.sub.2.4 Zr.sub.10 were produced in the same manner as Example 1
and were subjected to an X-ray diffraction. As a result, it was
confirmed that all of these alloys have amorphous structures. The
saturation magnetizations were 90, 77, 83 and 112 emu/g,
respectively, while the crystallization temperatures were
485.degree. C., 498.degree. C., 490.degree. C. and 482.degree. C.,
respectively.
[EXAMPLE 7]
Amorphous alloys of the present invention having compositions of
(Co.sub.0.9 Ni.sub.0.1).sub.90 Zr.sub.10 and (Fe.sub.0.7
Co.sub.0.3).sub.90 Zr.sub.10 were prepared together with
conventional amorphous alloys of Fe.sub.40 Ni.sub.40 P.sub.14
B.sub.6 and Fe.sub.40 Co.sub.40 B.sub.20 as references. These
alloys were subjected to a bending test after annealing at
100.degree. C. to 600.degree. C. in 30 minutes. As a result,
relationships between the bending fracture strain and annealing
temperature as shown in FIG. 5 was observed. In FIG. 5, axis of
abscissa and axis of ordinate represent, respectively, annealing
temperature and fracture strain E.sub.f. The thickness of the
samples was about 20 .mu.m. Characteristics of amorphous alloys
Fe.sub.40 Ni.sub.40 P.sub.14 B.sub.6, Fe.sub.40 Co.sub.40 B.sub.20,
(Fe.sub.0.7 Co.sub.0.3).sub.90 Zr.sub.10 and (Co.sub.0.9
Ni.sub.0.1).sub.90 Zr.sub.10 are denoted by numerals 1, 2, 3 and 4,
respectively.
From FIG. 5, it is shown that the amorphous alloy of the invention
has a higher embrittlement commencing temperature and, hence, a
higher thermal stability than the conventional amorphous alloy
having non-metallic content.
As has been described, the amorphous alloy of the invention has
superior magnetic and mechanical characteristics, as well as high
thermal stability.
Obviously, many modifications and variations of the invention are
possible in the light of the above teachings. It is therefore to be
understood that within the scope of the appended claims the
invention may be practiced otherwise than as specifically
described.
* * * * *